Tapered roller bearings are frequently used to support rotatable gears in transmission assemblies. These tapered roller bearings require a static preload in order to function properly. The preload must be properly set to maximize durability, and to minimize spin loss and noise. Achieving a desired preload is particularly important in a three axis transmission wherein transverse forces exist between adjacent axes, which adds additional variability to the stack up of components, and could adversely affect the preload.
One prior art method of establishing preload is to provide a preload adjustment nut at the end of the differential axis and transfer axis. However, this requires additional parts and introduces additional leak paths into the design.
A further prior art method includes an internal bolted clamp which establishes the preload within the transmission. This method results in packaging problems and added cost as a result of the additional parts.
A further prior art method is the use of a specialized gauge which measures a distance from the middle of the tapered roller bearings on each axis to the face of the respective case cover. A shim is then selected and positioned in a transmission housing pocket based upon this measurement. This method can be expensive and complicated, and may be problematic because the transmission assembly becomes a matched set which can never be separated or reused in another transmission without repeating the measurement process. The gauge can also be very expensive to design and build.